Tilted anisotropic Dirac cones in partially hydrogenated graphene

Abstract

By means of first-principles calculations, we predict a partially hydrogenated graphene system, ${\mathrm{C}}_{6}{\mathrm{H}}_{2}$, and find the one in $AB$-trans configuration is a Dirac material with a tilted anisotropic Dirac cone electronic structure. Different from graphene, in which the Dirac points are located at $K$ and ${K}^{\ensuremath{'}}$ and the Fermi surfaces are circular with doping, the $AB$-trans ${\mathrm{C}}_{6}{\mathrm{H}}_{2}$ exhibits Dirac points located on the lines from $\mathrm{\ensuremath{\Gamma}}$ to $M$ with quasielliptical Fermi surfaces when doped. Around the Dirac point, the Fermi velocity varies along different directions. Therefore, the propagation of charge carriers in this system is highly anisotropic, creating a new tunability for novel transport properties.